Co-Seismic Displacements of the 1992 Landers Earthquake Sequence
We present co-seismic displacement vectors derived from Global Positioning System (GPS) measurements of 92 stations in southern California. These GPS results are combined with five well-determined GPS displacement vectors from continuously tracking stations of the Permanent GPS Geodetic Array, as well as line-length changes from USGS Geodolite and two-color laser trilateration observations, to determine a self-consistent set of geodetic data for the earthquake. These combined displacements are modeled by an elastic dislocation representation of the primary fault rupture planes. On average, the model residuals are about twice the estimated measurement errors.
© 1994, by the Seismological Society of America. Manuscript received 29 July 1993. This study benefited from the field efforts of many people, including SCEC staff and UCLA and UCSD students, the staff of the USGS, engineers from the University Navstar Consortium (UNAVCO), and surveyors from state and county agencies. Bill Young of Riverside Co. Flood Control District and Jerry Stayner (County Surveyor, Riverside Co.), and also Larry Cotton (County Surveyor, San Bernardino Co.), gave much support in conducting the pre- and post-Landers field GPS surveys, and providing us with GPS data they collected prior to the Landers sequence for their own projects. Many GPS stations were provided by the Caltrans and NGS's HPGN project; these agencies also conducted extensive postearthquake field work and provided their data to the SCEC archive for use in this study. We would like to thank Larry Fenske, Bob Nelson, and John Fundus at Caltrans for access to the HPGN data. Some of the GPS stations used here were established in the STRC surveys led by Rob Reilinger at MIT. Reviews by D. Eberhart-Phillips, M. Murray, and J. Sauber helped to improve this manuscript. We especially thank M. Murray and D. Agnew for their efforts and their helpful and thorough commentaries. Funding for this work was from the USGS and NSF through the internal and external NEHRP programs and the SCEC. In part, this work was performed under the auspices of the Department of Energy by the Lawrence Livermore National Laboratory under contract W-7405-ENG-48. The work at Scripps is supported by NASA (NAGW-2641 and NAG 5-1917), NSF (EAR 92 08447), the Southern California Earthquake Center USGS cooperative agreement (14-08-00001-A0899), the USGS (1434-92-G2196), and Caltrans (53N195). SCEC Contribution Number 94.
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